It's Prenvo's Mobile Allowance for iPhone, and does one simple job undeniably well: it displays on-screen how many minutes and texts you have left to use from your monthly allowance, how much you've spent outside of that, and how many days remain until it's refreshed.
And it costs just 59p. All you do is enter the login details you use to access your account on O2's Web site, and the application pulls down your usage details. It's remarkably simple, very fast and works over 3G, EDGE or Wi-Fi.
Even Ian, who may well be the only person to hate everything about an iPhone just because it's an iPhone, conceded to be impressed: "Why this isn't on every phone made by every company, everywhere, ever, is a mystery," he said, before going back to his Android device feeling sorry for himself. Loser.
We'd add more screenshots over the page, but there isn't much more to show. After you input your login details once, all you see when loading the app is that screen at the top of this page. You can check it out in the iTunes App Store now (iTunes link).